Air-cooled turbocharger



Dec. 18, 1951 H. DAVIS AIR-COOLED TURBOCHARGER 2 SHEETS-SHEET l INVENTOR.

wn mzqw W 4 ATTORNEYS.

Filed Dec. 20, 1949 Dec. 18, 1951 AIR-COOLED TURBOCHARGER Filed Dec. 20, 1949 H. DAVIS Har I 2 SI-lEETS-SHEET 2 IN V EN TOR. W

Patented Dec. 18, 1951 asters; AIR-COOLED TURBOCHARGER Hunt Davis, Pittsburgh, Pa., assignor to Elliott Pennsylvania Company, Jeannette, Pa., a corporation of Application December 20, 1949, Serial No. 134,014

This invention relates to superchargers having turbines which are operated by hot exhaust gases,

and more particularly to the cooling of the bearings therein.

It is among the objects of this invention toprovide a supercharger in which the bearings that support the impeller and turbine rotor shaft are cooled by air from the impeller, and in which the construction is such that conduction and radiation of heat from the hot turbine parts to the bearings is reduced.

In accordance with this invention, a compressor casing and a turbine casing are disposed in axial alignment with each other, with their inner end walls spaced apart and provided with central openings. An annular web, or flange, concentric with the .axis of the casings and preferably integral with the compressor casing, connects the end walls together adjacent their central openings. A hearing housing projects from opposite sides of the inner end wall of the compressor casing inside the annular web. The housing is spaced a short distance from the annular web and the inner end wall of the turbine casing. The annular portion of the compressor casings inner end wall between the web and bearing housing is provided with circumferentially spaced air passages. A shaft is rotatably mounted in bearing means in the bearing housing and carries on its opposite ends an impeller and a turbine rotor. With this construction heat from the turbine casing can be conducted to the other casing and thence to the bearing housing only through the annular web, whose outer surface is exposed to the atmosphere and whose inner surface is cooled by air issuing from the passages in the compressor casing end wall. To reduce conduction of heat from the turbine rotor directly to the shaft, the rotor may be provided with a thin walled hollow hub projecting axially from its back side and telescoping a short distance over the adjacent end of the shaft, to to which it is rigidly connected. Radiation of heat from the turbine rotor to the bearing housing is reduced by an intervening shield that encircles the hub. Air that has flowed across the inner surface of the annular web then flows between this shield and the rotor hub and out through the turbine wheel.

The preferred embodiment of the invention is illustrated in the accompanying drawings, in which Fig. 1 is a view of the turbine end of the supercharger; Fig. 2 is an enlarged vertical section taken on the line II-II of Fig. 1, but with fragments shown in elevation; Fig. 3 is a 6 Claims. (01. 230-209) view of the inner end wall of the compressor casing looking in the direction of the arrows IIIIII of Fig. 2; and Fig. 4 is a fragmentary vertical section in the turbine casing taken on the line IVIV of Fig. 2.

Referring to the drawings, the compressor casing includes a hollow casing member having a cylindrical side wall I provided at its outer end with an integral end wall 2. The end wall has a large, central air inlet opening 3 in it which is encircled by an outwardly propecting cylindrical wall 4. The side wall of the casing member has, an outlet opening 6, from which extends a short conduit 1 provided with a bolting flange. The inner end wall of the compressor casing is a separate plate 8 (Figs. 2 and 3) that is secured to side wall I by screws 9. The central part of the plate is provided with an opening encircled by a tubular bearing housing I I integral with the plate and projecting about equal distances from its opposite sides. The housing is provided inside, near each end, with three radial spokes l2 whose inner ends are connected by a ring I3 that supports a bearing l4. Mounted on the inner end of the bearing housing is a disk It that is parallel to the outer end wall of the casing. The diameter of the disk is a little less than the inner diameter of the casing. A diffusing radial air pasage I1 thus is formed between the disk and the outer end wall of the casing all around the casing inlet.

Rotatably mounted in bearings It is a shaft l8 which extends almost entirely through the casing inlet. Rigidly mounted on the shaft extension is an impeller I!) of the conventional shrouded type provided with circumferentially spaced blades 20. When the impeller is rotated .by the shaft, it draws air in through the casing inlet 3 and forces it through diffusing passage l1 into the casing and then out through the casing outlet 6.

To drive the shaft a turbine rotor 22, adapted to be driven by exhaust gases from an internal combustion engine, is mounted on the opposite end of the shaft. As the exhaust gases will heat the rotor to a high temperature, conduction of heat therefrom to the shaft is reduced by connecting the rotor and shaft by means of a thin cylindrical wall. For example, the inner or back side of the rotor may be provided with a thin walled hollow hub 23 projecting axially from it. The outer end of the hub can be telescoped over the adjacent end of the shaft a short distance and welded to it. The result is that the turbine rotor is spaced from the shaft by a thin cylindrical wall that offers appreciable resistance to the flow of heat from the turbine wheel to the shaft.

The turbine rotor is mounted just inside the outlet 25 of a turbine casing that has in its side wall an inlet 26 from which a flanged conduit 21 extends outward. The turbine casing has a substantially fiat inner end wall 28 provided with a central opening through which bearing housing I I extends into the casing. This opening is large enough to space the inner end wall of the turbine casing a short distance from the bearing housing so that heat will not be conducted from the casing directly to the housing.

Another feature of this invention is that the two cas n s are connected together in such a manner that not much heat can be conducted from the turbine casing to the compressor casing, from which it would be conducted to the outer bearing in the bearing housing. The inner bearing, being completely inside the compressor casing, is surrounded by a stream of cool air and therefore is not in danger of becoming overheated. In accordance with this invention, the inner end walls of the two casings are connected together by an intervening annular flange or web 3| which spaces them apart. This annular web preferably is integral with end plate 8 of the compressor casing at a point close to the bearing housing. Therefore, the outer surfaces of the two inner end walls of the casings have the maior part of their areas exposed to the atmosphere and separated by it. Radiation of heat from the turbine casing to the compressor casing can be reduced by a shielding plate 32 between them connected to the turbine casing. The inner end wall of the turbine casing is joined tightly to the outer end of web 3| by means of screws 33 extending through circumferentially spaced thickened portions 34 of the web, from which integral ribs 36 may radiate across the plate to strengthen it. Heat that is conducted from the turbine casing to the bearing housing must therefore pass through the thin web and a narrow section of the end plate, except for an immaterial amount of heat that may be conducted through a pair of thin radial sections 31 which connect the web to the housing at top and bottorn to provide room for an inlet 38 and outlet 39 for lubricating oil that is circulated through the bearings. Thus, the spacing apart of the two casings reduces heat transfer between them, while conduction of heat is held low by the web that connects the casings. A large part of the heat entering the web is removed by the cool, moving air in the compressor casing at the compressor end of the web.

Another feature is that the web and the portion of the bearing housing outside of the compressor casing are cooled by some of the air from that casing. This is accomplished by providing the narrow section of end plate 8 between the web and the housing with a plurality of circumferentially spaced passages ll, through which some of the air in the compressor casing can escape and flow between the web and housing. This air is directed radially inward across the turbine end of the bearing housing by means of a dished bafile plate 42 (Figs. 2 and 4) which encircles the hub 23 between the housing and turbine rotor. The outer edge of the baflle plate is clamped in the turbine casing, while the inner edge is spaced a short distance from the hub to provide an annular passage through which the cooling air can flow into the space between the plate and the turbine rotor and thus cool he rotor. From there the air flows outwardly to the periphery of the rotor and then in between the turbine blades where it mixes with the exhaust gases. It will be seen that this air also helps to cool the rotor hub, and that the baiile plate also serves as a radiation shield to help protect the adjacent bearing and bearing housing from heat from the rotor. The air pressure in the space between the bafile plate and the bearing housing causes some of the air to pass end seal 43 and the adjacent bearing and create a slight pressure in the bearing housing, which helps to scavenge oil from the housing. It also reduces the tendency of oil to leak out along the shaft and through the seal.

According to the provisions of the patent statutes, I have explained the principle of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. A supercharger comprising a compressor casing and a turbine casing disposed in axial alignment with each other, said casings having inner end walls that are spaced apart and provided with central openings, an annular web concentric with the axis of said casings and connecting said end walls together adjacent said openings, a bearing housing projecting from opposite sides of the inner end wall of the compressor casing inside said web and spaced a short distance from the web and the inner end wall of the turbine casing, said end wall of the compressor casing between the web and bearing housing being provided with circumferentially spaced air passages, a shaft rotatably mounted in the bearing housing, and an impeller and a turbine rotor in said casings rigidly mounted on opposite ends of the shaft.

2. A supercharger comprising a compressor casing and a turbine casing disposed in axial alignment with each other, said casings having substantially parallel inner end walls that are spaced apart and provided with central openings, an annular web concentric with the axis of said casings and connecting said end walls together adjacent said openings, a bearing housing projecting from opposite sides of the inner end wall of the compressor casing inside said web, said housing being integral with the inner end wall of the compressor casing and spaced a short distance from said web and the inner end wall of the turbine casing, said end wall of the compressor casing between the web and bearing housing being provided with circumferentially spaced air passages, a shaft rotatably mounted in the hearing housing, and an impeller and a turbine rotor in said casings rigidly mounted on opposite ends of the shaft.

3. A supercharger comprising a compressor casing and a turbine casing disposed in axial alignment with each other, said casings having inner end walls that are spaced apart and provided with central openings, an annular web concentric with the axis of said casings and connecting said end walls together adjacent said openings, a bearing housing projecting from opposite sides of the inner end wall of the compressor casing inside said web and spaced a short distance from the web and the inner end wall of the turbine casing, said end wall of the compressor casing between the web and bearing housing being provided with circumferentially spaced air passages, a shaft rotatably mounted in the bearing housing, an impeller rigidly mounted on the end of the shaft in the compressor casing, a turbine rotor disposed in the turbine casing, and a thin cylindrical wall rigidly connecting the back side of the rotor to the shaft.

4. A supercharger comprising a compressor casing and a turbine casing disposed in axial alignment with each other, said casings having inner end walls that are spaced apart and provided with central openings, an annular web concentric with the axis of said casing and connecting said end walls together adjacent said openings, a bearing housing projecting from opposite sides of the inner end wall of the compressor casing inside said web and spaced a short distance from the web and the inner end wall of the turbine casing, said end wall of the compressor casing between the web and bearing housing being provided with circumferentially spaced air passages, a shaft rotatably mounted in the bearing housing, an impeller and a turbine rotor in said casings rigidly mounted on opposite ends of the shaft, and a plate supported by the turbine casing between the turbine rotor and the bearing housing to form a shield protecting the housing from heat radiated by said rotor.

5. A supercharger comprising a compressor casing and a turbine casing disposed in axial alignment with each other, said casings having inner end walls that are spaced apart and provided with central openings, an annular web concentric with the axis of said casings and connecting said end walls together adjacent said openings, a bearing housing projecting from opposite sides of the inner end wall of the compressor casing inside said web and spaced a short distance from the web and the inner end wall of the turbine casing, said end wall of the compressor casing between the web and bearing housing being provided with circumferentially spaced air passages, a shaft rotatably mounted in the bearing housing, an impeller rigidly mounted on the end of the shaft in the compressor casing. a turbine rotor disposed in the turbine casing and provided with a thin walled hollow hub projecting axially from its inner side and being rigidly connected to the adjacent end of the shaft, and a heatshielding plate supported by the turbine casing between the turbine rotor and the bearing housing, said plate having a central opening through which said hub extends, and there being a small clearance between the plate and hub for flow of air from said passages into the space between said plate and rotor.

6. A supercharger comprising a bearing housing, a radial wall encircling the central portion of the bearing housing and integral therewith, a shaft rotatably mounted in the bearing housing, an impeller and an exhaust gas turbine rotor rigidly mounted on the opposite ends of the shaft, a casing member encircling the impeller and connected to said radial wall to form a compressor casing, an annular web encircling the bearing housing in close but radially spaced relation thereto and integral with the turbine side of said radial wall, the outer surface of the web being exposed to the atmosphere, a turbine casing encircling the turbine rotor and spaced from said housing and radial wall, and means connecting the turbine casing to the turbine end of said web, said radial wall between the web and the bearing housing being provided with circumferentially spaced openings, whereby some of the air in the compressor casing can flow through the wall and across the inner surface of the web.

HUNT DAVIS.

REFERENCES CITED The following references are of record in the file of-this patent:

UNITED STATES PATENTS Number 

